Volume :

4

Issue :

1

Abstract :

This research work aimed for development of seismic hazard map for Shigo Kas hydropower project area based on extensive geophysical and geotechnical investigations. Seismic refraction survey was conducted on the lines at the important structures for the delineation of the subsurface lithology and other geophysical parameters. A comprehensive seismic layout plan consisting of fourteen lines (2.52 Kilometers) was formulated. The geophysical data was processed by computer aided software IXRefrax of Interpex Limited of USA to calculate the exact average velocities of the layers and depth of each layer under NSL. Four hundred meter rotary diamond drilling has been executed to confirm the seismic refraction survey results. The strata properties were used for site response analysis by DEEPSOIL software using ground motion data of Chi-Chi 1999 (TCU 078 EW) earthquake record form PEER data base. The maximum magnitude potential for the identified faults is calculated by Wells and Coppersmith, 1994 relationship. The study indicates that Main Mantle Thrust located 1.5 Km away from intake site with potential of 7.8 magnitude is the most seismogenic source. The shallow crystal earthquake model of Campbell Bozorgnia et al., 2008 has been used. NEES Integrated Seismic Risk Assessment Framework (NISRAF) developed by Sheng-Lin and Professor Elnashai at University of Illinois at Urbana-Champaign, USA has been used for deterministic seismic hazard map in form of contours. The PGA values at intake and power house are 0.50 g and 0.40 g.